STB is basically a Leopard with less gun accuracy but better turret and hull armor, Leopard 1 is other way around.

Neither can tank shells reliably, and both have fairly good mobility. And Pos is right, the STB grind is a bloody nightmare. At least the Leopard grind has the Ru 251 and the PT A to make it more fun and bearable (once you max them). The Type 61 and STA-1 have absolutely 0 reliable armor and massive tumors.